Fermented Foods                                                – Part 1 –

By Yorick Tromp 

Kefir is originally from the Caucasus Mountains and it is traditionally consumed in Eastern Europe, Russia and Southwest Asia. This fermented milk drink is produced using artisanal processes from the Caucasus people and since the 19th century kefir (in its many forms) has spread throughout the world for two very good reason: taste and therapeutic benefits. Of course taste is personal, however the benefits of kefir have extensively researched.

Kefir grains have a complex composition of sugars, proteins and microorganisms. The polysaccharides and protein form a matrix in which the microorganisms can survive and thrive. The bacteria in the grains predominantly consist of lactic acid bacteria, acetic bacteria, yeast and fungi. The exact microbial composition varies according to the kefir origin, the substrate used on which the grains grow (e.g.: cow’s milk or soy) and the culture maintenance method. However, all types of kefir have in common that the species of bacteria and yeast coexist in a symbiotic relationship. Moreover, similar to the intestinal microbiota, it is the diversity within this ecological system that ensures the stability and functionality of the bacterial and yeast species.

The kefir grains ferment the substrate on which they grow, similar to yoghurt starters which ferment milk to yoghurt. This fermentation process leads to a wide variety of bioactive compounds. These compounds can act together to produce  various health benefits attributed to kefir consumption. Due to this activity and its bacterial composition kefir is considered to be a probiotic.

Historically, kefir has been recommended for the treatment of several clinical conditions such as gastrointestinal problems, hypertension and allergies These health effects caused by kefir consumption may be due to a combination of factors. Besides competitive exclusion in the mucosa of the GI tract, kefir produces antimicrobial compounds, such as organic acids, peptides, hydrogen peroxide and ethanol. These compounds have a beneficial effect on the reduction of pathogens and prevention and treatment of gastro intestinal infections. Moreover, stimulation of the immune system has been observed in several animal models, most likely due to the production of the exopolysaccharides. Kefiran, for instance was able to balance the immune cells in the intestinal mucosa (1). Furthermore, components of kefir seem to suppress the Th2 immune response by influencing the secretion of proinflammatory cytokines (1). Most kefir grains also have the ability to breakdown lactose, due to the β-galactosidase enzyme activity in the bacterial cells.

It is becoming more and more clear that kefir can be considered a probiotic product or a functional food. The beneficial effect of kefir is highly dependent on the bacterial and yeast composition. Most likely the more diverse this community of microorganisms is, the more effective the kefir grains. Of equal importance is the substrate on which the kefir grains are grown. Winclove is now actively researching the possibility to harness the potential of kefir into a probiotic product.

More info: Yorick.tromp@winclove.nl

References

1. Vinderola et al. Immunomodulating capacity of kefir. J Dairy Res. 2005; 72:195-202.